辽西北地区45年来年降水量时空分布特征

Spatial and Temporal Characteristics of Annual Precipitation in Northwestern Liaoning Province in Recent 45 years

辽西北地区是辽宁省的重点旱区。选择该地区39个雨量站1966～2010年共45年的年降水资料,利用EOF分解和小波分析方法,研究了该地区降水的时空特征。结果表明,辽西北年降水量由东南向西北递减;45年来全区平均年降水量无显著增加或减小趋势,主要表现为丰枯周期变化;EOF分解的前三个特征向量累积方差达到74.9%,代表的空间变化型分别为全区降水一致型、东南与西北相反型、东部与西部相反型;第一特征向量时间系数随年份的变化与降水距平的年际变化极为相似,存在明显的17、9、4年周期;第二特征向量时间系数存在29～33、12年周期;第三特征向量时间系数存在29～33、6～7年的周期变化。

By collecting annual rainfall data of 39 stations from 1966 to 2010, empirical orthogonal function （EOF） decomposition and wavelet analysis are used to study the temporal and spatial characteristics of rainfall in Northwestern Liaoning Province, where is the major dry area in Liaoning Province. The results show that the annual precipitation decreases from the southeast to the northwest and the spatially average precipitation has no significant trend of increasing or decreasing, but mainly periodic variation. According to the results of EOF, the cumulative variance of the first three ei genvalues attains 74.9%, which represent the typical rainfall pattern field of the same anomaly in the whole area, the opposite anomalies between southeastern and northwestern, the opposite between east and west; the temporal variation of the time coefficient of the first eigenvalue is similar to that of the annual rainfall, existing periods of 17 years, 9 years, and 4 years; the time coefficient of the second eigenvalue has periods of 29-33 years and 12 years while the time coefficient of the third eigenvalue has periods of 29 33 years and 6-7 years.